Adding solutions for homework4
Alternative implementation of list-to-number

- using drop-while and reduce
Adding homework6 for lab1.
Updating grades for homework4.
Adding the example problems from the 6th on-site lab.
Adding the tasks from lab 6
Adding grades and solutions to homework5 for lab1.
Adding missing closing paren.
Merge branch 'master' of https://github.com/gshopov/fp2013 into my-solutions